1. Field of the Invention
This invention relates to a process for preparing blocked derivatives of m- or p-isopropenyl-xcex1, xcex1-dimethylbenzyl isocyanate (m-TMI(copyright) polymerizable isocyanate and its p-isomer), which derivatives are particularly suitable for use as wet adhesion promoters for latex polymers and paints derived therefrom. More specifically, the invention relates to the preparation of these monomers directly from in or p-isopropenyl-xcex1,xcex1-dimethylbenzyl carbamic acid ester which are Intermediates in the production of the corresponding Isocyanates. The invention additionally relates to the use of m- and p- isopropenyl-xcex1,xcex1-dimethyl benzylamines (m- and p-TMA) as adhesion promoters for latex polymers, paints, sealants and caulks.
2. Description of Related Art
EP127802 discloses producing isopropenyl-xcex1,xcex1-dimethylbenzyl amines (m-TMA and p-TMA) by the hydrolysis of the corresponding isocyanates, m- and p-TMI, respectfully. U.S Pat. No. 4,927,969 discloses an alternate process whereby M-TMI is reacted with ethanolamine followed by thermal cracking of the resulting hydroxyalkylurea to m-TMA and ethylene carbonate. Isopropenyl-xcex1,xcex1-dimethylbenzyl amines are recognized by those of ordinary skill in the art to be particularly useful as monomers which can be incorporated into polymers to introduce crosslinking sites.
The conventional method of preparing blocked derivatives of isopropenyl-xcex1, xcex1-dimethylbenzyl isocyanate (TMI(copyright)) involves reacting the isocyanate TMI(copyright) with an appropriate blocking group which is either an amine, a hydroxy or a lactam derivative. For example, W091/12243 discloses reacting TMI(copyright) with an aminoethylethyleneurea (AEEU) to produce the wet adhesion monomer shown below: 
WO91/12243 discloses that this reaction is advantageously carried out in a solvent such as ethyl acetate.
U.S. Pat. Nos. 5,252,689 and 5,208,347 similarly disclose the preparation of blocked derivatives of TMI(copyright) using TMI as the staring material.
A limitation to the commercial use of blocked derivatives of TMI(copyright) has been that the conventional preparation methods, employing TMI(copyright) as the staring material, can be somewhat expensive. TMI, like other isocyanates, requires special handling procedures and the reaction with amino-functional blocking derivatives can be exothermic and thus require careful manipulation.
It has now been surprisingly discovered that certain blocked derivatives of TMI can be prepared more economically, that is, directly from the precursor m-or p-isopropenyl-xcex1, xcex1-dimethylbenzyl carbamate ester, by heating the precursor with an appropriate hydroxy, amino lactam or cyclic urea functional blocking group.
The monomers prepared by the process of this invention are useful to promote adhesion in polymers and copolymers, including use in aqueous emulsion copolymer latices which are used to prepare latex paints.
Latex-containing surface coatings and coating compositions having superior wet adhesion properties may therefore be produced by including in the monomer system one or a mixture of monomers produced by the present invention""s novel process. Also, blends of latices modified with the monomers of the present invention may be used with unmodified latices to achieve the desired degree of wet adhesion.
It has also been discovered that wet adhesion properties can be imparted to aqueous emulsion copolymer latices by incorporating into such latices isopropenyl-xcex1,xcex1-dimethylbenzyl amines (m- and p-TMA).
In accordance with the present invention, there is provided a novel process for preparing blocked derivatives of isopropenyl-xcex1,xcex1-dimethylbenzyl isocyanate (i.e., blocked derivatives of p- or m-TMI(copyright)), comprising the step of contacting m-or p-isopropenyl-xcex1, xcex1-dimethylbenzyl carbamate ester with a hydroxy, an amino, a lactam or a cyclic urea functional blocking group at a temperature and for a length of time sufficient to prepare a blocked derivative of p- or m-TMI(copyright).
The invention further provides compounds of the following general Formula I, below, as functional monomers useful for imparting wet adhesion to water based paint and coating compositions. 
wherein X is xe2x80x94NH2 or xe2x80x94NHCOZ;
wherein Z is xe2x80x94NHR1R2, 
wherein R1 or R2 is, individually, H or a C1-C4 alkyl and p is 1 or 2.
Thus, the invention is also directed to latex compositions comprising compounds of the general Formula I as wet adhesion promoters.
It is a further object of this invention to provide economically obtainable novel compounds of the Formula II, below: 
wherein Y is 
The present invention is a process for preparing blocked derivatives of TMI(copyright) via the direct reaction of m-or p-isopropenyl-xcex1,xcex1-dimethylbenzyl carbamate esters with a hydroxy, an amino, a lactam or a cyclic urea functional blocking group.
The term xe2x80x9cTMIxe2x80x9d in the context of the present invention, refers to isopropenyl-xcex1, xcex1-dimethylbenzyl isocyanate (m-TMI(copyright) polymerizable isocyanate and its p-isomer). TMI(copyright) is a commercially available product from Cytec Industries, Inc., West Paterson, N.J. Its synthesis is described in U.S. Pat. No. 4,439,616, which is herein Incorporated by reference for all purposes as if fully set forth.
The synthesis of m- and p-isopropenyl-xcex1,xcex1-dimethylbenzyl carbamate esters, designated as m-TMU and p-TMU, respectively, are disclosed in U.S. Pat. No. 4,439,616.
This invention relates to the preparation of blocked derivatives of TMI, including compounds of the general Formula III, below: 
wherein G is: NHR1R2
wherein R1 or R2 is, individually, H or a C1-C4 alkyl, n is an integer of from 2 to 4, inclusive, p is 1 or 2 and R3 is a C1-C4 alkyl.
The monomers of the present invention are useful as chemical intermediates. They copolymerize with many other monomers, both under solution and emulsion polymerization conditions. The polymers and copolymers are especially useful as adhesion and wet adhesion promoters.
The monomers shown in Formula III, above, are advantageously prepared by reacting m- or p-isopropenyl-xcex1,xcex1-dimethylbenzyl carbamate esters (i.e., m- or p-TMU) with an amino, a hydroxy, a lactam or a cyclic urea functional blocking group in the presence of heat and a suitable catalyst. The reaction is generally conducted at a temperature in the range of from about 70xc2x0 C. to about 120xc2x0 C. Preferably, the reaction is carried out at a temperature of between 80xc2x0 and 100xc2x0 C., until the removal of alcohol by-product is complete.
The resulting solid derivatives can be purified by crystallization, if desired, from a suitable solvent such as ethyl acetate, chloroform, and the like. The crude products may optionally be dissolved in appropriate solvents for further end-use applications. For example, in latex applications, the monomers may be dissolved in acrylic acid, methacrylic acid and their esters, styrene, xcex1-methylstyrene or mixtures thereof. Monomers which are soluble in water may be supplied for end use applications in water or mixtures of water and methacrylic acid.
The 4,439,616 patent discloses the preparation of mixtures of TMU and TMXDU which are thermally cracked directly to mixtures of corresponding isocyanates, TMI and TMXDI, respectively. The patent further discloses separation of TMU from TMXDU by vacuum distillation, which may result in poor yields of TMU due to its cracking to TMI under the distillation conditions (180-200xc2x0 C.). In order to obtain high yields of TMU, in pure form, for the process of the present invention, the mixture of TMU and TMXDU, produced by reacting m-diisophenylbenzene (m-DIPEB) with methyl carbamate (MeC), is neutralized, excess MeC is removed by distillation, and the solvent heptane is subsequently added to the reaction mixture. Addition of the solvent heptane results in efficient extraction of TMU from the TMXDU, since TMU preferentially dissolves in heptane. Solvents similar to heptane which may also be employed to obtain similar results, include hexane, octane, cyclohexane, and mixtures thereof.
Examples of suitable hydroxy functional blocking groups employed in the reaction include hydroxyalkylalkyleneureas such as hydroxyethylethyleneurea (HEEU) and hydroxyethylpropyleneurea (HEPU), dialkylaminoethanol and dialkylaminopropanol.
Examples of suitable amino functional blocking groups employed in the reaction include aminoalkylalkyleneureas such as aminoethylethyleneurea (AEEU) and aminoethylpropylene-urea (AEPU), N,N-dialkylaminoethylene diamine and N, N-dialkylaminopropylene diamine.
Examples of suitable lactams include pyrrolidone and caprolactam.
Examples of suitable cyclic ureas include ethylene urea and propylene urea.
The condensation reaction of TMU with an amino, a hydroxy, a lactam or a cyclic urea functional blocking group may optionally be carried out in the presence of a non-hydroxylic, non-reactive solvent. Suitable non-hydroxylic solvents include toluene, glymes, acetonitrile and dimethylformamide (DMF). Low melting, polar materials such as hydroxyethylethylene-urea (HEEU) and aminoethylethyleneurea (AEEU) do not require such solvents.
A catalyst is not necessary for the reaction, but, if desired, a catalyst may be added to accelerate the reaction. Examples of suitable catalysts which may be used include ZnCl2, Zn(OCOCH3)2, FeCl3, cobalt acetate, chelates of transition metal ions with xcex1, xcex2-diketones and ketoesters; titanium catalysts, such as tetraisopropyl tartrate; tin salts such as SnCl2, SnCl4, SnO2 and tin based catalysts such as dibutyltin dilaurate, tetrabutyidlacetoxystannoxane, dimethyltin dilaurate, stannous octoate, tetrabutyl diacetoxy stannoxane (TK1(copyright) from Takeda Chemical Co.1), dibutyltin oxide and the like. The preferred catalysts are tin compounds. The amount of catalyst generally used is in the range of from about 0.1 to 5.0 mole % based on TMU. Preferably, the range of catalyst used is from about 0.2 to 0.5 mole%.
The blocked isocyanate monomers which may be prepared by the process of the present invention are represented by the Formula III, above. Although monomers of the Formula III, wherein G is 
are known as wet adhesion promoters, a new method for their preparation has herein been discovered. Additionally, although the compounds of Formula III, wherein G is 
are known compounds which can be made by the present invention""s novel process, their use as wet adhesion promoters has herein been discovered.
Furthermore, compounds of the general Formula II, wherein Y is NH2 or 
which may also be prepared by the novel process of the present invention, have herein been discovered as novel compounds, useful as wet adhesion promoters.
Although compounds of the Formula I, wherein X is xe2x80x94NH2, that is, m- and p-isopropenyl xcex1,xcex1-dimethylbenzylamines (m- and p-TMA), are known compounds, not produced by the present invention""s novel process, their use as wet adhesion promoters has herein been discovered.
Representative examples of the monomers which have herein been discovered to function as useful wet adhesion promoters are listed below. m- and p-isopropenyl-xcex1,xcex1-dimethylbenzyl amines (m- and p-TMAs), N-hydroxysuccinimide blocked TMI, hydroxyethylethyleneurea-blocked TMI, aminoethylethyleneurea-blocked TMI, N,N-diethylethylene diamine-blocked TMI and ammonia-blocked TMI.
It has also been discovered that blocked derivatives of m- and p-TMI may also be prepared by reacting m- and p-diisopropenyl benzenes, respectively with urea or urethane derivative of the blocking groups in the presence of acid catalyst such as p-TSA, H2SO4, etc. This is illustrated by the synthesis of pyrrolidone blocked m-TMI (monomer M11) from m- diisopropenyl benzene and pyrrolidone urea (N-carbamyl pyrrolidone). 
The monomers of the present invention find use, for example, in adhesives, caulks, sealants, coatings, wood coatings, can coatings, paper coatings, marine coatings, architectural coatings, automotive coatings, non-wovens, binders, wett/dry strength resins for paper, textiles, lubricants, modifiers for cement, mortar and concrete, intercoat adhesion promoters, polymer compatibilizers, pressure sensitive adhesives, primers, surface modifiers, corrosion inhibitors and formaldehyde scavengers. A particularly preferred use of the monomers of the present invention is as wet adhesion promoters.
The monomers of the present invention are polymerizable or copolymerizable through the unsaturation in the compounds. They may be used as comonomers in monomeric systems for forming aqueous emulsion polymers, including in compositions comprising monomers such as acrylics, vinyls, vinylacrylics, vinylaromatics, xcex1,xcex2-unsaturated carboxylic acids and their esters, as well as other known specialty monomers. Examples of suitable acrylic monomers include methyl acrylate, ethyl acrylate, methyl methacrylate, hydroxyalkyl acrylates, hydroxyalkyl methacrylates, butyl acrylate, hexyl acrylate, cyclohexyl acrylate, 2-hydroxyethyl methacrylate, 2-ethylhexylacrylate, 2-hydroxyethylacrylate, 2-hydroxypropyl methacrylate, 2-hydroxypropyl acrylate, piperidinoethyl methacrylate, morpholinoethyl methacrylate, and the like.
Examples of suitable vinyl monomers include ethylene, propylene, butylene, isobutylene, hexene, vinyl acetate, vinyl esters of versatic acid (i.e., VEOVA -9 and VEOVA -10), vinyl chloride, acrylonitrile, acrylamide, methacrylamide, vinylidene chloride, oleic acid, linoleic acid, 1,3-butadiene, isoprene, norbornene, cyclopentadlene and the like.
Examples of useful unsaturated carboxylic acids include itaconic acid, citraconic acid, crotonic acid, mesaconic acid, maleic acid, fumaric acid, and the like; xcex1,xcex2-unsaturated dicarboxylic acid esters of the dicarboxylic acids described above including aromatic esters, cycloalkyl esters, alkyl esters, hydroxyalkyl esters, alkoxy alkyl esters, and the like.
Examples of suitable vinyl aromatic monomers, with which the present invention""s monomers can be polymerized, include styrene, xcex1-methylstyrene, vinyltoluene, ethylstyrene, isopropylstyrene, p-hydroxystyrene, p-acetoxystyrene, p-chlorostyrene and p-chloromethyl-styrene.
In particular, the monomers of this invention may be incorporated in effective amounts in aqueous polymer systems to enhance the wet adhesion of paints made from the polymers. Maleuric, fumauric, citraconuric, itaconuric acids and their alkyl esters may also be incorporated in effective amounts in aqueous polymer systems to enhance the wet adhesion properties of paint compositions.
The emulsion polymers used in formulating latex paints usually are all acrylic copolymers comprising alkyl esters of acrylic and methacrylic acid with minor amounts of acrylic acid, methacrylic acid, acrylamide or methacrylamide, or they are vinyl/acrylic polymers comprising vinyl containing monomers or polymers in combination with softer acrylic monomers. The commonly used ethylenically unsaturated monomers in making acrylic paints are butyl acrylate, methyl methacrylate, ethyl acrylate, 2-ethyl hexyl acrylate, and mixtures thereof. In acrylic paint compositions at least 50% of the polymer formed is comprised of an ester of acrylic or methacrylic acid. The vinyl-acrylic paints usually include ethylenically unsaturated monomers such as vinyl acetate and butyl acrylate or 2-ethylhexyl acrylate. In vinyl acrylic paint compositions, at least 50% of the polymer formed is comprised of vinyl acetate, with the remainder being selected from the esters of acrylic or methacrylic acid.
The monomers of this invention may be added to a monomer composition from which acrylic or vinyl acrylic polymers are formed in a concentration which may vary over a wide range. Preferably the concentration is at least sufficient to improve the wet adhesion of paints made from the polymer composition. Concentrations may range from about 0.05% to about 20%, by weight, based on the total weight of monomers. Preferably, the concentration is in the range of from about 0.1% to about 5.0%, and more preferably from about 0.5% to about 3.0%.
The monomer composition may be used in conjunction with other ongredients, such as various free radical catalysts to initiate polymerization, emulsifying agents to protect particles from agglomeration, and buffers to maintain a desired pH during polymerization, as is generally well-known to those of ordinary skill in the art of polymerization. For example, suitable free radical polymerization catalysts are the catalysts known to promote emulsion polymerization and include water-soluble oxidizing agents such as organic peroxides (e.g., t-butyl hydroperoxide, cumene hydroperoxide, etc.), inorganic oxidizing agents (e.g., hydrogen peroxide, potassium persulfate, sodium persulfate, ammonium persulfate, etc.) and those catalysts that are activated in the water phase by a water-soluble reducing agent. Such catalysts are employed in a catalytic amount sufficient to cause polymerization. Generally, a catalytic amount ranges from about 0.01 to 5.0 parts per hundred parts of monomer. As alternatives to heat and catalytic compounds to activate polymerization, other free radical producing means, such as exposure to activating radiations, can be employed.
Suitable emulsifying agents include anionic, cationic, and nonionic emulsifiers customarily used in emulsion polymerization. Usually, at least one anionic emulsifier is utilized and one or more nonionic emulsifiers may also be utilized. Representative anionic emulsifiers are the esters of sulfosuccinic acid, amides of sulfosuccinic acid, alkyl aryl sulfonates, alkali metal alkyl sulfates, the sulfonated alkyl esters and fatty acid soaps. The emulsifying agents are employed in amounts to achieve adequate emulsification and to provide desired particle size and particle size distribution.
Examples of suitable buffers used to maintain a desired pH during polymerization include ingredients such as acids, salts, chain transfer agents and chelating agents. For example, if the polymerization constituents include a monoethylenically unsaturated carboxylic acid comonomer, polymerization under acidic conditions (pH 2-7, preferably 2-5) is preferred. In such instances, the aqueous medium can include those known weak acids and their salts that are commonly used to provide a buffered system at the desired pH range.
The manner of combining the polymerization ingredients can be various known monomer feed methods, such as, continuous monomer addition, incremental monomer addition, or addition in a single charge of the entire amount of monomers. The entire amount of the aqueous medium with polymerization additives can be present on the polymerization vessel before introduction of the monomer, or alternatively, the aqueous medium, or a portion of it, can be added continuously or incrementally during the course of the polymerization.
The polymerization of the monomer system which includes ethylenically unsaturated monomers and either one or more of the the novel monomers of the present invention can be accomplished by known procedures for polymerization in aqueous emulsions, as disclosed, for example, in U.S. Pat. Nos. 3,366,613; 4,104,220; 2,881,171; 4,219,452 and EPO 626672A2, which are incorporated by reference herein for all purposes as if fully set forth. Pre-polymer monomeric starting materials used to form polymeric pre-emulsion compositions using the monomers of the present invention are typically dissolved or suspended in the aqueous medium to a desired concentration. Preferably, the polymerization of the invention is performed at a concentration range of about 10 weight-% to about 70 weight-% of the monomers in the aqueous medium, although somewhat higher or lower concentrations may be employed in some cases.
By way of example, polymerization is initiated by heating the emulsified mixture with continued agitation to a temperature usually between about 500C to about 11 00C, preferably between 60xc2x0 C. to about 100xc2x0 C. Heating of the emulsified mixture is also preferably conducted in an inert atmosphere (e.g., purging with nitrogen, argon, etc.). Polymerization is continued by maintaining the emulsified mixture at the desired temperature until conversion of the monomer or monomers to polymer has been reached.
Generally, depending upon the final application of the polymeric composition, the polymer may contain anywhere from about 0.05 weight-% to about 20.0 weight-% of the monomer of the present invention (based on the concentration of the monomer), preferably from about 0.1% to about 5.0 weight-% of the present monomer, and more preferably from about 0.5% to about 3.0 weight-% of the monomer of the present invention.
In addition to making emulsion polymers, it is contemplated that the monomers of the present invention be used to form solution copolymers. Polymerization towards the formulation of solution polymers may be completed under substantially similar circumstances as described above for emulsion polymerization except that the medium of polymerization in a solution polymerization reaction is organic instead of aqueous. Generally, the solution polymerization reaction is carried out with the monomers in solution in an inert organic solvent such as tetrahydrofuran, methyl ethyl ketone, acetone, ethyl acetate, or other suitable organic solvents such as hexane, heptane, octane, toluene, xylene and mixtures thereof. In the case of water-soluble monomers, inverse emulsions may also be prepared. Inverse emulsion being defined as a water-soluble polymer system dispersed in an organic solvent. Preferred solvents are non-toxic and odorless.